noun
barking at nothing; barking at passers-by or visitors
Describes a dog barking without a clear threat, often at strangers or trivial stimuli. Can be used literally or figuratively for pointless complaining.
隣の犬の無駄吠えがうるさい。
The neighbor's dog's barking at nothing is noisy.
彼の批判は単なる無駄吠えだ。
His criticism is just pointless barking.
遠吠え means 'howling' (often at a distance), while 無駄吠え specifically refers to barking without a good reason.
Compound of 無駄 (むだ, 'useless, pointless') and 吠え (ぼえ, 'barking', from 吠える). Literally 'useless barking'.